Association of increased tracheal mucus accumulation with poor willingness to perform in show-jumpers and dressage horses

The objective of this study was to examine the association of pharyngeal lymphoid hyperplasia (PLH), recurrent laryngeal neuropathy (RLN), mucus accumulation (MA) score and tracheobronchial secretion neutrophil percentage (TBS-N) with rider-assessed performance in sport horses. Airway endoscopy scores, tracheobronchial secretion cytology, rider-assessed general impression and willingness to perform were investigated in 171 top-level sport horses.Increased MA appears to be associated with poor willingness to perform in sport horses. Older horses had decreased PLH scores and increased TBS-N. Mucus accumulation scores ⩾3 were associated with increased odds (mean 9.92; upper and lower 95% confidence intervals: 1.5–64.6) of poor rather than excellent willingness to perform. A TBS-N of 20–50% compared with <20% was associated with decreased odds (median 0.11; upper and lower 95% CI: 0.02–0.66) of poor rather than excellent willingness to perform. In addition, horses with an RLN grade ⩾2 had significantly higher odds for giving a poorer general impression and willingness to perform. This finding, however, must be interpreted with caution, since only two horses had significant RLN (grade ⩾3).